Motor-control system



n. E. DE CAMP. MOTOR CONTROL SYSTEM.

APPLICATION FILED OCT- 6| 19'5- REYNE WED MAR. 30, I92;

Reverse INVENTOR Ray E. De Camp.

a'n'onun WITNESSES:

UNITED STATES l AT ENT OFFICE.

MY E. DE GAME, OF WILKINSBUBG, PELINSYLV ANLA ASSIGNOB T0 WESTINGHOUSEELECTRIC AND MANUFACTURING COMPANY, A CORPOQIION OF PENNSYLVANIA.

' mororecon'rnor. srsrmr.

Specification of Letters Yatenti" Patented Sept. 28, 1920.

Application filed October 6, 1918, Serial No. 124,043. Renewed Batch 30,1920. Serial No. 370,049.

To all whom it may cmwem:

Be itkn'own that I,- RAY E. De CAMP, a citizen of the United States, anda resident of Wilkinsbur in the county of Allegheny and-State ofennsylvania, have invented a new and useful Im rovement in Motor- IControl Systems, of w iich the following is are employed in connectionwith electric motors for driving planers or similar machines requiringfrequent stops and reversals.

My invention has for its object to rovide a system of theabove-indicated c aracter which embodies means for preventing theclosing of the motorcireuit for operation in different directionssimultaneously and for insuring the opefiiing of the controllingswitches in a predetermined order.

In the operation of electric motors which are brought to rest by dynamicbraking by means of a local cir lit comprising the motor armature and te starting resistor, it is essential that the resistor be inserted incircuit with the motor armature before the main circuit of the motor isopened.

I. provide an arrangement whereby the reversing switches of an electricmotor are electrically interlocked in order to prevent theirsimultaneous closing. The starting resistor is controlled by anaccelerating switch. A relay that is operatively connected to theaccelerating switch maintains the closure of one of the reversingswitches until the accelerating switch has opened to 'insert theresistor in circuit with the motor or of thedyilamic braking circuitupon the opening of the reversing switch- In the accompanying drawing.the single figure! is a diagrammatic view of circuits and apparatusembodying my invention.

Line conductors 1 and 2. which may be connected to any suitable sourceof direct current, supply energy to an electric motor having anarmaturewinding 3. a series field-magnet winding 4 and a shunt fieldmagnetwinding 5. A starting resistor 6' is controlled by an acceleratingswitch 7 having an actuating coil 8. A relay 9 is me chanicallyconnected to the switch 7 to open and close when the switch 7 occupiesits corresponding position.

The main circuits of the motor are con trollcd by double-throw reversingswitches 11 and 12 that are respectively provided with actuating coils13 and 14. The circuits of the actuat' coils of the several switches arecontrolle by push button switches 15, 16 and 17 which operate to produceeffects upon the operation of the motor corre sponding to the legendsplaced :idjacent to t 1e respective switches.

7 To start the motor in the forward dircc tion, the push button switch'16 is awarded to complete a circuit which oxtcmls 'From the positiveline conductor 1 through switch 16, actuating coil 13 and back contactMia-1' bers of switch 12 to line conductor 2. The coil 13 is energizedto close switch 11 and thus complete the armature circuit of the motorwhich extends from line conductor 1 through series field-magnet Winding4. switch 11, armature 3. starting resistor 3, and back contact membersof switch 12 to line-conductor 2.

The motor then operates in the forward direction. hen the speed of themotor reaches a rate at which its counter-electromotive force has apredetermined value. the coil 8. which is connected across the tcrminals of the motor armature. is eucrgizcd to close switch 7 and therebycomplete a shunt circuit for the resistor 6. The pi1sl1buttonswitch'lfi'should be held in its closed position until the switch 7closes to cfi'cct the closing of relay 9. The latter. upon closing.completes. a shunt circuit for the pushbutton switches 15 and 16 andcloses a holding circuit for the actuating coil 13.

To stop the motor. the push button switch 17 is actuated to open thecircuit of the actuating coil 8 and thereby cause the switch 7 to openthe shunt ciicuit for the resistor 6. The opening of relay 9. whichoccurs simultaneously with the opcning of switch 7, opens the holdingcircuit of actuating coil 13. The snitch 11 then opens to complete adynamic braking circuit for the motor which extends from one terminal ofthe motor armature through the back contact members of switches ll and12, resistor 6. and fieldmagnet winding 4 to the other terminal of themotor armature. The motor is then brought quickly and safely to rest. vI

To start the motorih the reverse direction, the push button switch 15 isclosed to com lete the circuit of the actuating coil 14 of t e switch12. This circuit extends from linelconductor 1, throu h switch 15, coil14 and backcoptact mem rs of switch 11, to line conductor 2. The switch7 closes in the manner previous] described in connection with the forwarrotation of the motor; The relay 9 again closes a shunt CiI'CUltfor'each of the switches 15 and 16.v The latter switch may then hereleased, the relay 9 maintaining a'holding circuit for the coil 14. Themotor is stopped in the manner described above.

It will be noted that, when-switch 11 is in its closed position, it isimpossible to efi'ect the closingof switch 12 because the switch 11,upon-closing, opens the circuit traced above, of the coil 14 at the backcontact members of the switch 11. Independently of this circumstance, itis not possible to efl'ect theclosing ofjthe switch-12 when the switch11 occupies its closed position because the switch 11, upon closing,estab-f lishes a shunt circuit'for the actuating coil 14 which extendsfrom 'the switch 11, through the actuating coil 14 and the relay. 9, tothe other terminal of the switch 11. A similar double efi'ect isobtained for the circuit of the coil 13 upon the closing of the switch12. It'will be im ssible, therefore, to efi'ect the closing 0 either ofthe reversing switches when the other occupies its closed position, Asabove stated, the relay 9 establishes a shunt circuit for each of thepush-button switches 15 and 16, v A single set of'contacts, controlled bthe accelerating switch, operates to estailish shnnt'circuits for thecontrolling push-button switches when the motorais in operation,

so that the actuating coil of thereversing switch operated will remainexcited, and that reversing switch constituting a shunt for theactuating coil of the other reversing switch.

I claim as my invention:

1. In a motoncontrol system, the combination with an electric motor, apair of reversing switches and an accelerating switch, of means forefl'ecting the closing of each of said revrsin switches, said meansrolliprising a contlo ling switch and said other reversing switch whensaid other. reversing switch occupies an inoperative position, and

means controlled by said accelerating switch and operative inconjunction with snidother reversing switch, when said other reversingswitch remains in said inoperative position, to maintain said firstreversing switch closed until said auzclerating switch is opened.

2. In a. motor-control system, the combinntion with an electric motor. apair of reyersing switches and an accelerating switch, of means foreffecting the closing of each of said reversing switches, said meanscoin- 'lin ass-1.17s

prising a controlling switch and said other reverslng switch when saidother reversing switch occupies an inoperative position. and

In a control system, the combination.

with a 'pair of switches each adapted to orcupy a normal sition, and anactuating end for each 0 said switchesadapted to cause the actuation ofits corresponding switch to a second sition, of a second pair ofswitches each a apted to cause the encrgization of one of said coils toci'lcct said actuation of said corresponding switch, the circuit of theactuating coil ofcach of said first pair of switches includin saidcontrolswitch for said coil an the other of sai first pair of switcheswhen said" other switch occupies said normal position, and means forshort-circuiting said controlling switch from said circuit butmaintaining said other of said first pair ofswitches in said circuit.

4. In a motor-control system, the combination with an electric motor, apair of reversing switches therefor each adapted to occupy an o ativeposition and an inoperative position, and an actuating coil for each ofsaid' switches, of a second pair of switches each adapted to control theenergization of one of said coils, the circuit of the actuating coil ofeach of said re-. versing switches including said controlling otherreversing switch when said other re-- versing switch occupies itsinoperative position, a second pair of switches each adapted to closethe circuit of one of said coils, an accelerating switch, and a relayfor maintaining the circuits of said coils closed that ismecha'nically'connected to-said accelerating switch and is electricallyconnected in series with each of said switches when said switches occupytheir inoperative positions and the coil of the other of said switchesand in parallel to said controlling switches.

In testimony whereof, I have hereunto ilbseribcd my name this 28th dayof Sept,

RAY E, DE CAMP.

